1. Field of the Invention
The present invention relates generally to transporting disabled vehicles and, more particularly, is concerned with a recovery unit for hitching a disabled truck tractor to a towing truck tractor in a manner comparable to normal tractor trailer operations.
2. Description of the Prior Art
In view of the extensive use of truck tractor and trailer rigs in transporting the bulk of good and freight over the nation's highways, it is to be expected that tractor breakdown will be a frequent occurrence. Typically, a disabled tractor has to be removed from the highway to a service facility in order for repairs to be made. Removal normally requires towing the disabled tractor by using a large tow truck specially equipped and dedicated for that purpose. Such tow trucks are expensive, costing in excess of $100,000, and entail high operating costs. In many areas of the country, there are either none available or there may be considerable delay in obtaining the services of one when a breakdown occurs.
There has earlier been disclosed the desirability of temporarily adopting an ordinary truck tractor to perform such towing tasks in addition to its normal use as part of a tractor and trailer rig. The objective is to eliminate the need to locate a dedicated tow truck in order to remove a disabled tractor from the highway to a service facility. The advantage in being able to use another tractor is that such tractors are found with much greater frequency in all parts of the country than are dedicated tow trucks and thus one would quite likely be quickly and conveniently available where the need might arise. Representative hoist and towing mechanisms devised for this purpose are disclosed in U.S. Pat. Nos. 4,047,773 to Parks; U.S. Pat. No. 4,544,175 to Hubert and U.S. Pat. No. 4,708,358 to Gehman, et. al.
The mechanisms disclosed in the aforesaid patents recognize the advantage of employing the fifth wheels on both the towing and towed tractors to achieve a secure coupling of the two vehicles. Such coupling with the fifth wheel has been recognized to impart pivotal mobility necessary for maneuverability of the coupled vehicles during travel. However, the mechanisms of the aforesaid Patents do not readily permit unrestricted pivotal movement at the fifth wheel of the tow tractor. Unrestricted turning movement of a typical fifth wheel is achievable only when said wheel is in a level position, otherwise, binding of rotational movement is experienced. None of the aforesaid patent disclosures are cognizant of this important factor. Additionally, any secondary fulcrum or point of support on the tow tractor other than its fifth wheel inhibits maneuverability.
Earlier towing devices are difficult to deploy for use, often involving the need to carefully position beams or assemblies that may weight as much as 500 pounds. Another requirement of an effective tow device is compactness of storage upon the towing vehicle.
Once the towing tractor is coupled to the disabled tractor, it is necessary to lift the rear portion of the disabled tractor so that it can be pulled in a rearwardly directed manner, riding only upon the front wheels. Such lifting is a formidable task because a tractor may weigh between 15,000 and 20,000 pounds, and a force of about 8,000 pounds is required to raise the rear end of the tractor so that only its front wheels ride on the ground. The aforesaid Gehman, et. al. patent discloses the use of three hydraulic cylinders within a complex framework system to achieve the lifting function. The cylinders must be activated alternatively in a precise order to unfold the unit, and again to lift the tractor. Most of the lifted weight rests upon a fulcrum located behind the rearmost wheels of a tandem axle towing tractor. The placement of excessive weight behind the rear axle or the centerline of tandem rear axles of the towing tractor is undesirable because it lightens the load on the front steering axle of the tractor, thereby causing problems with steering, braking and legal weights per axle. It should also be noted that, in the aforesaid patents, the towing vehicle is of comparable size and weight as the disabled tractor. It would be desirable to utilize a smaller, less expensive towing vehicle to accomplish the lifting and towing mission.
It is accordingly an object of the present invention to provide apparatus for enabling a vehicle having a fifth wheel to tow a disabled tractor vehicle, also having a fifth wheel.
It is another object of this invention to provide apparatus as in the foregoing object which lifts the rear of said disabled vehicle for transporting it rearwardly while rolling on its front wheels.
It is a further object of the present invention to provide apparatus of the aforesaid nature wherein all the lifted weight of said disabled vehicle is borne by the fifth wheel of said towing vehicle.
It is yet another object of this invention to provide apparatus of the aforesaid nature which couples said towing and disabled vehicles by way of their fifth wheels.
It is a still further object of the present invention to provide apparatus of the aforesaid nature which permits jackknifing of said coupled vehicles in a small turning radius.
It is an additional object of this invention to provide apparatus of the aforesaid nature of simple construction amenable to easy, safe operation and low cost manufacture.
These objects and other objects and advantages of the invention will be apparent from the following description.